Ellipsograph.



G. E. DEXTER.

I BLLIPSOGRAPH. APPLICATION FAILED JUNE 8, 190a.

Patented Aug. 31, 1909. j

avweutoz 6/20/1965 Qexfer.

witness m MW NITED STATES nimrsoonnra.

PATENT: oFrIoE.

Application filed June 18', 1908. Serial No. 487,827.

. To all whom it may concern:

principal object the provision of an exceedmay ngly sim lo and inexpensive drawing instrument ymeans of which ellipses of various degrees of curvatl-lre may be quickly andaocurately described. I

To this end, the invention, briefly described,comprises a cruciform body portion or trammel, the arms of which are longitudinally grooved, and a beam or marker-oarry-' ing arm provided with a pair of slidable clamps whose position upon the beam may be adjusted atjwill, said clamps including angular bases which fit in the grooves abovementioned. i

tical longitudinal plane of which coincides with the-like named plane of the arm, di-

; rectly below which opening is etched a short line which bifurcates the lower edge of said face, one of said openings (preferablythat one which is formed .in the lower vertical arm.) being. arranged to receive a fin er formed upon the mner face'of a hol er whose outer face is provided with a pointer, it being. thus. possible to dispose the instrument with absolute accuracy with respect to the known lines which are to serve as the I axes of'the ellipse.

The invention. still further resides in the particular construction of the clamps carried by the beam, and in the specific device employed in connection with the beam for retaining. the marker,.z'. 6., the pen or pencil in lace during the movement of the beam he referred embodiment of the invention is ilustrated in the accompanying drawings, in. which corresponding parts are des- Specification oil etters Patent.- Patehted Aug. 31, 1909.

ignated by the' same reference numerals throughout the several views.

Of the said drawings, Figure 1 is a perpective view of the complete invention.

s lig. 2 is an'enlarged detail View of one of.

the clamps carried by the beam. Fig. 3 is a perspective View of the holder. 5 are transverse sections taken respectively on the lines 4.4= and 5-5 of Fig. 1.

Referring more particularly to the drawings, 1 des gnates generally the body portion of the instrument, which, as shown, has a cruciform shape, the upper face of the body portion having formedgtherein a pair of grooves 2 and '3 which intersect. each other at right angles and are arranged longitudinally of the four'arms of which said body portion consists. The inner or base' portions of the grooves above referred to are triangular in cross section, the grooves opening through. the end faces of the arms as shown in Fig. 1. Directly below the bottom wall of each groove, and disposed in the central vertical longitudinal plane of the corresponding arm is an inwardly-extending opening 4 which is angular in cross section and communicates at its inner end with a threaded passage 5 which opens outwardly through one or the other of the side faces of the arm. and is adapted to "receive the stem of a screw 6. The end face of each arm is further provided with a vertical division line 7 which is etched or otherwise marked'thereon and is located directly below the corresponding opening 4, the lower end of each line bifurcating the lower edge. of

the end face upon which it is indicated. The

division lines above referred to are formed at right angles. to the lower edges of said end faces and for this reason coincidewith the axes of the corresponding arms. The body portion of the instrument includes-1n addition a detachable holder 8 which 1s designed to. be connected to that arm of the body portion whose axis coincides with the lower half of the minor axis of the ellipse,

Figs. #1 and the holder having formed upon its inner face, or secured thereto as preferred, a horizontal finger 9 adapted to t in the opening 4 in the arm above referred to, the holder being retained against displacement by means of the adjacent screw (5 whose inner end is brought into binding COI1l32lCl3 W1lZh said. finger when the screw is turned 1n the proper direction. The outer face of the holder is provided with a pointer 10 which projects forwardly from the lower edge of said.

disposition of the division lines 7 upon the,

end faces of the arms which, together, form the major axis of the instrument, it will be apparent that the latter may be positioned with absolute accuracy with respect to a pair of intersecting lines indicated upon the plotting board and designed to form the axes of the ellipse to be described.

In connection with the body portion above described, there is employed a scale arm or beam 11 whose upper face is graduated as shown, said arm terminating at one end in a claw 12 provided with a depending finger The beam carries a pair of sliding clamps 14, each of which, as shown in Fig. 2, includes a triangular base portion 15 arranged to fit loosely in the lower portions of the cross grooves 2 and 3, an annular upper portion 16 which embraces the beam, and a.

neck portion 17 which connects said upper and lower portions, the annular upper portion of each slide being provided with a threaded opening in which is fitted the stem of a binding screw 18, the screws being tightened to hold the clamps against displacement when their position upon the beam has been adjusted.

The claw 12 above referred to serves to retain a pencil, pen, or other marking device in vertical position during the movement of the beam, the body portion of the instrument bein steadied by the holder-" which is held firm'y by the draftsman who operates the beam with one hand in the usual manner, while he presses upon the holder withthe other hand.

The length of the arms of the instrument may be increased by means of joints 19 each of which is provided with a groove 20 having the'same cross-sectional dimensions as the corresponding groove 2 or 3, to permit the requisite registration of the grooves when the joints are attached to-the body portion by means of the fingers 21 with which their inner faces are provided, said fingers fitting in the openings-4 in the end faces of the ortion. The joints are arms of the body held against .acci entaldisplacement by means ,of the screws 6. The fingei's 9 and 21 are of such c'ross'section as to permit them to fit tightly in the openings 4.

The groove 2. formed-in the arms which constitute the major axis of the instrument has its inner orbase portion slightly eplarged, and its neck portion constricted with respect to the corresponding portions of the groove 3, such construct-ion preventing the angular base of the clamp-which slides in the first mentioned groove from entering the inner face arm; an

groove in which the second clamp travels, and vice versa. w

The body portion may be made in various sizes is preferably constructed of brass, while the beam 1s formed of nickeled steel with the graduations etched thereon. It is to be understood, however, that the instrument as a whole ma be constructed of any other desired materia The upper portion 16 of each clamp 14 has preferably formed therein a sight openin 22 through which the graduations marks on the beam are visible, the lower wall of each openin extending upwardly intermediate its en s, as indicated by the numeral 23,each of such extensions serving as an indicator. or pointer.

What is claimed is:

1. An .ellipsograph, comprising a cruciform body portion each arm of which has an inwardly-extending opening formed in the end face thereof, and a member detachably connected to one of said arms and having its rovided with a lateral finger arranged to t in one of the openin s in said arm and its outer face rovide pointer whose axis coinci es with that of said arm.

2. An ellipsograph comprising a crucifo'rm body portion each arm of which has an inwardly-extending opening formed in the end face thereof, the principal vertical longitudinal plane of the opening coinciding with the like-named plane of the arm; and a member dctachably connected to one of said arms and having its inner face rovided with. a lateral finger arranged to t in one of the openings in said arm, and its outer face provided with a ointer whose axis coincides with that of S316. arml 3, An ellipsograph comprising a cruciform body portion each arm of which is provided with an inwardly-extending opening formed in the end face thereof, and with a vertically disposed division line located directly below the opening and bifurcatin the lower edge of said ace, the principa vertical longitudinal lane of the opening coincidin 'with thli e-named plane ofthe a member detachably connected to one of said arms and having its inner face of the instrument which with a v rovided with a lateral .finger arrangedto t in one of the openings in said arm, and its outer face provided with a. ointer whose axis coincides with that of sai arm whereby the instrument may be accurately posi-' tioned with reference to a pair of known in tersecting lines which serve as the axes o the ellipse to be-described.

4. An ellipsograph comprising a cruciform body portion having its" upper face providedwith a air of intersecting grooves disposed longitudinally ofthe 'arms'of said body portion, each arm having an inwardly extending opening formed in the end face thereof, and a vertically disposed ldivision line located directly below the opening and bifurcat-i'ngthe lower edge of said face, the principal vertical longitudinal plane of the opening coinciding with the like-named plane of the arm.

5. An ellipsograph comprising a cruciform body portion having its upper vface provided with a pair of intersecting grooves disposed longitudinally of the arms of said body portion, a beam, and a pair of sliding clamps carried by the beam and fitting in the grooves, one of said grooves having a greater cross-sectional area than the other groove, to prevent the clamp fitting in the first mentioned groove from entering the last-mentioned groove. I

(S. An ellipsograph comprising a cruciform body portion having its upper face provided with a pair of intersecting grooves k disposed longitudinally of the arms of said body portion each groove including a base portion angular in cross-section and a constricted neck, a beam, and a pair of sliding clamps carried by the beam and litting in the grooves, one of said grooves having its base portion of greater cross-sectional area and its neck of less cross-section area than the other groove, to prevent the clamp fitting in either groove from entering the other groove.

In testimony whereof, I atlixf my signature, in presence of two witnesses.

CHARLES F. DFXTER, Witnesses L. M. GiomNos, \V. H. (JiUY. 

